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  • Alright, folks, welcome back. Okay. So, I will say a few words about science in general. Okay? So chemistry is one of the natural sciences. It has a long history, and I will spend about ten minutes

  • kind of motivating

  • why it is what we're doing and why we will be doing it in a particular way. This also holds for physics and for geoscience, whatever kind of natural science we're dealing with; same kind of methods,

  • same kind of history

  • so I like this picture- a lot of things are beautiful

  • and that you might have gotten those moments- I think we all have- where you look up at the sky or something else around you wonder, you know, how can all of this be? Why is it so beautiful and amazing?

  • One way to address that

  • and try to get a grip on all these

  • beauties around us is to kind of, you know, give a scientific description.

  • or put some elements in place.

  • and that is more easily said than done. And it's always

  • fun to realize

  • put yourself in this situation thousands of years ago. Say you're one of those

  • greek thinkers, and you lie on your back, and you look at the starry night, and you wonder, what is that light

  • in the far distance. What is that?

  • right now we know it's a star. Our sun

  • is a star, too. We know that.

  • back in the day, of course, they did not know. How do you actually come to such a conclusion? That is not trivial.

  • Right now in our lifetime we know so much

  • we take a lot of knowledge for granted. Knowledge has accumulated over the years.

  • But this is not trivial stuff. All of this knowledge took time to build up.

  • So it's fun to realize that sometimes it's actually

  • not trivial

  • to come to a certain conclusion.

  • So these people live in those

  • ages where not a lot of things were known.

  • And they were starting to think about

  • what is matter? I mean, how should we

  • think about matter? Can we give proper descriptions of matter?

  • So this person, Thales,

  • he says everything is made out of water

  • Okay? So he is trying to understand why do certain materials have certain properties, and his way of thinking about it had to do with, maybe it contains different amounts of water

  • Maybe water acts in a particular

  • way in different materials.

  • Democritus says, "well, I don't think that's the case." He says,

  • "I think materials are based on an accumulation of

  • many many many many tiny little particles

  • altogether

  • that are, in turn, indivisible ones.

  • stopped the most fundamental level there is a type of

  • pull that bring particles together

  • and they form the material on a larger scale

  • is the atomistic theory

  • that we know now is the best way to think about materials. But in those days, they did not know.

  • So Democritus is actually

  • a person that lived at a later time

  • than Thales,

  • however

  • Aristotle, you may know him,

  • was a person that lived at a later time than Democritus and

  • he did not believe this assertion

  • of Democritus

  • he said

  • he said something...about... (laughter)... the computer stopped.

  • he says speak the materials are not made out of indivisible particles, but they are composed of different amounts

  • of fire, earth, water,

  • air, and aether.

  • So it's a very different way of thinking about materials.

  • Now all these things, they can be true, I mean,

  • how do you know? I mean, at some

  • level you can say anything you want.

  • So how are you going to discriminate

  • between different

  • world views, if you want.

  • So how can we be sure that

  • if we know know Democritus is probably

  • the person that gave the best description but how do we know that?

  • Well, it turns out that if you actually start to do experiments and test things

  • over and over and over again, if you at some point can arrive at conclusions that make more

  • sense, more sense than other conclusions,

  • and then at some point you may be able to rule out

  • some hypotheses and confirm

  • others.

  • So basically, you take materials, you start to

  • look at them very carefully, manipulating them, do experiments on them,

  • a whole series, and

  • based on the logical kind of deduction, you can

  • arrive at certain conclusions.

  • So this is something people started to do

  • very early on, but really

  • they were ramping up

  • in medieval times

  • and accumulated

  • into kind of the method

  • that we now call the scientific method.

  • So this is kind of like the early days, and in terms of chemistry those were the alchemists

  • and they were really fascinated of course by

  • turning everything in to gold. Everybody wanted to be rich,

  • and if you're a poor person,

  • of course what you want is more money

  • and the way to get that is to have more gold.

  • If you can turn

  • dust to gold, then you are golden.

  • but you have to be able to do that, and so in order to

  • do that, motivated by this, say, pressure for economic

  • welfare, you start to experiment, sort of manipulate, and you actually

  • discover a whole bunch of properties of matter that you have not encountered before.

  • and here is a person that was also in that tradition

  • one of the later ones, okay? So this is

  • almost leaving the medieval times here

  • and he says

  • 'why don't you just like, forget about

  • making gold but instead use the

  • methods that we've been

  • working with to do something good?"

  • For instance, finding medicines.

  • He is a person who was very

  • motivated by helping other

  • folks, other people, medically.

  • he said, 'the best way I can do that is by

  • actually using these methods like observing, experimenting, trying to understand

  • how the human body works, and then try to help this person.

  • This may seem very trivial, but this was not trivial because most

  • medical practices were based on mystic beliefs that did not necessarily have anything to do with a logical deduction of observations. Where you use the observations.

  • Okay, so he actually

  • used observation and

  • logical deduction

  • and did something good. For instance, he says

  • infection comes from outside the body, okay? Which is something that people did not know.

  • People thought that if you got an infection, it comes from you,

  • because you did something bad. Now we know it's a little microorganism that attacks you and sits there and causes problems.

  • He did through observing that, you take those states out of people in situations,

  • you actually have less infection.

  • He was still like a person of his time. For instance,

  • he still believed in bloodletting.

  • Cleansing through bloodletting. That was something disproven, but this

  • because the belief was so strong

  • we still thought it was a good practice.

  • Okay. So that leads us here

  • basically we have this method of trying to get closer to, um, I wouldn't say the

  • truth, necessarily, but to a better description of what matter is.

  • And so I want to make the distinction here that that method is

  • very different from

  • an opinion.

  • Scientific inquisition is not

  • coming up with better opinions.

  • So for instance, if this person says

  • "that's how it is"

  • he may say, "it's not."

  • he will say, "yes it is," he will say, "njet!" Okay? So these people have different opinions, and they will

  • never agree on anything.

  • But it's very hard to make sense of this.

  • Okay, so opinions are great

  • for a whole bunch of purposes, the driving force within our society, it does a lot of good, but then it comes to

  • finding the proper descriptions of nature, this is not a good

  • way to go about it.

  • Scientific inquisition is very different

  • and, you know, this is kind of like a very

  • short explanation of how the method works: you have a

  • clear observation of an event,

  • you give a very

  • proper description

  • of that event, which is frank.

  • Which is as frank as you can be.

  • Not biased

  • by what you want it to be

  • okay? This is really the difference between

  • opinion and scientific inquisition. You have to leave everything that you believe out of your system and just let the observation do its work. This is really hard for people, but that's really important. So,

  • a detailed description

  • of the phenomenon by frank observation

  • try not to be biased, or colored,

  • in your observation.

  • Then, you come to the interpretation. For instance,

  • This is Newton

  • you all know the example

  • apple falls, he gives a very detailed description

  • of what he saw,

  • the apple was sitting there, it was coming loose,

  • fell to the ground very close to him,

  • he gave a very detailed description, and then he says, well I can explain that if i come up

  • with this formula, of course the story is much longer than that,

  • but he has a formula and then -- very important,

  • you take that

  • interpretation

  • and you test it again

  • is this interpretation true under all circumstances?

  • it means that if an apple falls from this

  • tree,

  • is this also true for

  • another apple from a different tree?

  • Or from a different object? For instance, if I go and launch it from a building, Does it also obey this law?

  • If given,

  • It this law describes the falling of objects

  • throughout, then

  • you can give this a certain amount of credit, so to speak, in the sense that

  • this is a good description

  • of falling materials.

  • This is not an opinion. At all.

  • This is scientific inquisition.

  • Okay. So this of course is also the method that we

  • follow in chemistry

  • so let's say we have a beaker with chemicals, we do an experiment,

  • something changes.

  • you provide detailed descriptions of these

  • changes

  • of these phenomena

  • then we come up with an interpretation

  • For instance, this substance

  • must be a reducing agent. Okay? That is an interpretation, and with a hypothesis, you have to test it. Okay? We go back

  • change something,

  • for instance, say, if this were a reducing agent,

  • if I put a lot of, you know,

  • oxidizing agents in there,

  • the reaction must be different

  • and so you do that, and indeed if it is different,

  • then you actually strengthen your hypothesis.

  • okay, several times, until

  • you've exhausted all possibilities, and then you can

  • conclude that this must be an actual description of this

  • situation here.

  • again, this is not an opinion.

  • You cannot just say, 'oh, I think this is a reducing agent. It must be so.' No,

  • you actually investigate that scientifically.

  • All right, here's a couple of people,

  • so after medieval times people started to use that method

  • consistently

  • Robert Boyle is one of these people,

  • and he, through that method, that scientific method,

  • actually uncovered a lot of different kinds of

  • laws that are enveloped into chemistry. For instance, the gas law

  • and the differences between

  • compounds and mixtures. That was one of Boyle's contributions.

  • also the preposterous theory of matter

  • was reaffirmed

  • he brought back this idea

  • from Democritus

  • long forgotten because Aristotle had dominated the way people thought about matter. He said, 'hold on a second

  • my experiments indicate that

  • if you assume that

  • materials are made out of indivisible particles, I can explain all my observations.' Therefore,

  • this must be

  • a better description

  • than the description based on, for instance,

  • earth, fire,

  • air,

  • and aether. Right? So,

  • based on that,

  • he could throw out Aristotle's description as

  • not being a good description

  • no hard feelings, just not a good description.

  • All right, another person